Myocardial ischemia or myocardial infarction can produce areas of scar tissue in the myocardial substrate that will be unresponsive to cardiac pacing. If a patient having myocardial scar tissue requires cardiac pacing, the location of the scar tissue is preferably avoided in positioning pacing electrodes. However, the location of the scar tissue may be unknown without performing imaging procedures, such as magnetic resonance imaging (MRI), which may be costly, require catheterization or contrast agents, and may not be readily available in some geographic areas.
Cardiac resynchronization therapy (CRT) is one type of cardiac pacing therapy that is used as a treatment for heart failure patients in which one or more heart chambers are electrically stimulated (paced) to restore or improve heart chamber synchrony. Achieving a positive clinical benefit from CRT is dependent on several therapy control parameters including selection of pacing site(s) and the relative timing of pacing pulses delivered in the right and/or left ventricles. For example, selection of a CRT pacing site that avoids myocardial scar tissue is important in achieving clinical benefit. Systems and methods are needed for identifying myocardial scar tissue versus healthy myocardial substrate at a potential pacing site in a patient receiving CRT or other pacing therapy without requiring costly imaging technology.